Dear all,

My name is Jeff from Aruba and have an E55 AMG 2003 model also known as the legend. I have a strange problem that comes and goes when it wants concerning the brakes which is really annoying.
Please remember I live on an Island and we do have an official MB dealer, put please don't tell me to go there. Last time I brought my car I had to explain how to do the oil change...
Any way the problem is that I get a message during driving that say's Stop brake defective stop vehicle, this message is including the loss of the brakes (no power assistant from that moment). So I assume the systems stops working completely which is really dangerous.
When i stop the car, I turn of the ignition and start it again, everythings works fine. Like there was no problem before. However it comes back, sometimes after 1 minute sometimes after a day. Sometimes 3 times in a row in 3 minutes, sometimes all day without...
So you can see it is very annoying. And until today I did not had any time to go to the MB dealer the get the faults codes out of the system, but I will do this this week.

What can cause this strange problem, how is it possible that when i turn on / off the ignition (even during driving) the systems starts working again.
During the same time i discovered another strange thing. When I open the door, the air pump briefly turns on. This is a normal process which I also have seen with my E500. However since I have this strange error in the SBC system, I can turn on the air pump briefly by pressing the brake pedal? Which seems really strange, because this not sound like it should turn on the air pump when hitting the brakes. What can be wrong with this systems. What is bothering me is that is comes and goes when it wants. When it comes, it stays on untill I switch of the ignition and start it again. I can do this also during driving. By the way I don't think it is the brake switch causing the problem.

Please give me some advice how to do some self diagnostics before the dealer start swapping parts and is making bills that have to many figures.

What you're calling an "air pump" is actually the hydraulic pump that makes your brakes work. When you push the brake pedal on your car, you're only pushing against a spring and a sensor that tells the computer how hard to apply the brakes. When the hydraulic pump that the computer depends on for pressure quits making pressure you no longer have good brakes on the front and no brakes at all on the back of the car. As you use the brakes during normal driving, the pump will switch on for several seconds at a time to recharge the accumulator (where brake fluid is stored under pressure, similar to a water pressure tank on your home's well pump system). Sounds like your pump doesn't kick on every now and then, and your car doesn't like when that happens.

Lots and lots of good reading on this subject both on this site and on the world wide youtube - do a search for "how do my SBC brakes work?" and become enlightened. If nothing else, you'll be able to tell the dealer in more detail what's wrong and you'll understand why they want to charge you anywhere from $1200 to $2000 to fix your brakes. It is a job you can do yourself, but you will need a mercedes specific diagnostic computer (DAS-Xentry) to do it right. It's your way of stoppng a 4,000 pound projectile. Do it right, or have them do it for you.

TLDR: It sounds to me like your hydraulic brake pump is going out.

Edited to add: You should probably stop driving the car until the problem is fixed...

Okay, I understand it is the hydraulic pump, which sound valid because when the error occurs "Stop Brake defective! Stop vehicle!" the hydraulic pump does not make any sound and therefore no pressure and no brakes! If I assume correct based on what you told me above?
In this situation, (after we have all the fault codes). What is the procedure? You replace the complete system? Or you replace the pump only? There are also stories about the fact that the system can only handle 300.000 braking requests and therefore the system can be rebooted with a 25% till 100% device that I have seen in different you tube movies? But I think this is a different error called the C249F.

Any way any help is welcome, trapped on this Island with only one E55.

A useful thread...

https://mbworld.org/forums/e-class-w...pump-w211.html

Thanks for the link!!!

We have the fault code...
N0.: 1
DTC C26FB
Description: Control unit A7/3n1 (SBC(Sensotronic Brake Control) control unit), internal fault.
Sate: Current and stored.

And now... the official MB dealer seems not to be interested to fix it, if the part(s) are not bought there and they ask 100% margin on parts. The rumor goes that they never fixed this kind of problem ever before.

What to do... all help is welcome.

Suck it up and pay the dealership to do the work. They have done it before. They will get it right or you will be in their face until they do. Your car is not safe to drive the way it is. Do you have a better option?

Well I am not going to suck it up that easy. I am sorry. So I looked and found a company, please let me know if anybody has experience with it.

https://modulemaster.com/rebuilds/sh...s-sbc-rebuild/

This site is all about DIY and you'll find plenty of support if you go that route. You will need the DAS/Xentry computer though.

Sorry if that sounded harsh. Just don’t drive it the way it is. Rapid is right, if you have access to Star and the desire to do it yourself, the forum will support you. Again sorry if I seemed to come on too strong.

He Guys it is at the MB dealer, all is good the car seems to be in a perfect condition only one fault code the 7A\3n1 with is a faulty sbc control unit probably related to the pump or motor. Because you cannot buy the sbc control unit new, we take it to the module master. The complete de-installation and installation will be done by an experienced mb magician. And they are okay with the fact that it goes to the module master. They will test it when we receive it back. Of course I have to sign a disclaimer because the mb dealer will not be responsible for the moduel master but that is okay with me. And they were checking if the was still warranty on this for my benz, but i think that chance is zero.

I am very happy about all because the problem seems to be fixed under the 1.000 dollar. About 600 for tthe module master and 400 for the installation and bleeding including materials.

Thanks for the support and information appreciate it.

I have the same problem with my Merced but I found out there is a recall for this issue. I have taken my car to a MB dealer and they are working on this issue without me paying.

Not a recall. Warranty extended to 25 years. There is a difference.